Primo's Illegitimate Child
by noyamanoruri
Summary: If Tsuna was sent to the past by a malfunctioning bazooka with a body of a child and no means to survive, what was he to do? Pretend to be Primo's illegitimate child, of course. Post-Canon.
1. Prologue

**Title:** Primo's illegitimate child

 **Summary:** If Tsuna was sent to the past by a malfunctioning bazooka with a body of a child and no means to survive, what was he to do? Pretend to be Primo's illegitimate child, of course. Post-Canon.

 **A/N:** I do not own KHR. Characters are OOC to fit the flow of the story. Not beta-ed.

* * *

 **Prologue:**

It was inevitable, really.

Ever since Reborn sent his tutoring advertisement to his house, Sawada Tsunayoshi's life had been filled with nothing but chaos. After all, if you're the heir of the most powerful mafia famiglia, how normal could your life get? It was like asking Reborn to stop taking sadistic pleasure in tortur – tutoring Tsuna, which was practically impossible.

So when Lambo's ten-year bazooka was coming his way, the most foremost thought in his mind was to move away. The scene from when they were sent to the future flashed in his mind, and he immediately thought that he never wished to confirm his fear that he really became the boss of the family by going to the future –again. The only problem was, he was currently tied to his chair and was forced to sign the Vongola paperwork he knew nothing about, and the lock on the chains confining him was currently at Reborn's possession. The only things in his reach were a fountain pen and some sheet of paper, which would not really help in diverting the coming predicament.

What else was he to do?

Nothing.

He sighed and closed his eyes, praying to whoever deity was listening that he better not be waking up inside a coffin this time. Knowing you'd be dead ten years later was never good, no matter what Reborn might say.

When the pink smoke subsided and Tsuna found himself in the middle of what looked like an Italian street from more than a hundred years before that he had only seen in history books, with a body of an eight-year old child for more than five minutes already, he knew that something was definitely wrong.

It was inevitable, really. After all, when it comes to luck, Tsuna always has the worst of it all.

* * *

 **A/N: Updates for this story will be done sporadically, only if I have time in my schedule. Sorry in advance.**


	2. Chapter One

**A/N:** This chapter's release is faster than most, since the prologue part is very short. I just like to remind everyone again that updates are done sporadically. Thanks for the reviews, favs and follows!

I do not own KHR. Everyone are mostly OOC. Not beta-ed

* * *

 **Chapter One:** I'm getting tired of all this time travelling.

 _The subject of Primo's illegitimate child had been considered as a legend, a rumor circulating the Vongola ever since the time of Secondo. It was said that the child, who looked so much like Primo and whose name no one wanted to mention, was the one who defeated the Calesca Famiglia, the most ruthless Mafia in Sicily, when the said famiglia tried to kidnap him without knowing that he was the child of Vongola Primo. No official document relating to the said child was ever found, and everyone involved with this topic seemed to be really tight-lipped, but a lot of letters and diaries of the various family members and servants that had been preserved revealed mentions of a 'young master' or 'Primo's child' whose power and charm exceeds even those of his father's. Further research had been unsuccessful._

 _-The History of Vongola, on the rumors of Primo's illegitimate child_

 **Before the fateful moment, inside the Sawada residence**

"Tsuna-san, Lambo not doing homework!"

"Lambo, you can only have a snack after you finish your homework." Reminded a particular brunette.

"Not fair, Tsuna! Ipin's class didn't get any homework."

"According to my ranking, Ipin's class get the least homework in the whole second grade!"

Sawada Tsunayoshi, an ordinary but clumsy second year high school of Namimori High (and the future Vongola Decimo/Neo Vongola Primo, if Reborn had his way), looked up from the documents he was working on to look at the source of the noise, his three adopted siblings in his room, working on their homework. Since the representative battle three years ago, his daily life only consisted of insanity, chaos…

"Dame-Tsuna, did you finish those documents I gave you yesterday?"

…And paperwork. Piles and piles of paperwork.

"Yes. It's on that pile there." He pointed to an absurd amount of paper piling up on the other side of the room and watched as Reborn took out a small box similar to the future's box weapon and used it to store the enormous amount of paperwork Tsuna worked hard on. He really should cut the budget for the Vongola Engineering Department. It was because of them that Reborn had the easiest time in bringing in more documents for him to sign.

Reborn pocketed the storage box and Tsuna found himself staring at Reborn's hands. They were still smaller than his, but because Tsuna had resigned himself to the fact that he would never grow much, he knew that it would only take two years at most before Reborn would outgrew him. Sometimes, Tsuna wondered on how fast Reborn and the other Arcobaleno grew up. Before he was the same height as Lambo and Ipin, but in just two years, the hitman looked to be about Fuuta's age. Right now, Reborn could even pass as a short high school student. It might have been the work of Verde, since all the Arcobaleno seemed to wish to grow up fast, but he never found the courage to ask why.

Speaking of why…

"Hey, Reborn… Why do I still need to do some of the paperwork for Grandpa? It has already been a year since he fainted, right?"

"Stupid. If Nono pushes himself too hard, he's more likely to faint again." A sadistic smirk appeared on Reborn's face that caused shivers to run down the young heir's spine. "If that happened, your inheritance as the next boss will come sooner."

"I told you already, I'm not gonna be the next boss."

But with the way things were going, it seemed more impossible for Tsuna to escape that responsibility.

After Reborn came back with the permission from the ninth about his new tutelage as the Neo Vongola Primo, his life consisted of constant hellish training, school lessons, Italian lessons, etiquette lessons and a couple of assassinations here and there. Somehow, even though Tsuna didn't want anything to do with the mafia world, he still took those lessons as seriously as he could, if only to save his room from Reborn's wrath. Of course they all constantly go to trips, like every time Yamamoto had baseball games and everyone would come to watch, or the Vongola-style field trip where they traveled all around Japan in Giannini's flying bus, or visiting Gelaro*, Tsuna's former snow guardian in Catafalco Island to ski during winter vacation together with the Shimon family.

But one year ago in his first year in high school, Tsuna received the news that the Ninth fainted in the middle of working. There were already rumors about the Ninth being on the verge of death circulating in the Underground. Even if it was not real, the fainting episode would serve as an opportunity for other families to attack. To prevent that from happening, Tsuna and his guardians were sent to Italy (literally, in Tsuna's case, as he just woke up sitting in the plane with his mother laughing at his side talking about how happy she was with the opportunity to see his father working in Italy) with the pretense of having a late summer vacation.

In the end, Tsuna wasn't even able to enjoy the sights of Italy. His idiotic father took his mother, together with the girls and the kids, on a tour of the country. Gokudera seemed very eager to learn the tasks of a right-hand man from the Ninth's storm guardian and was listening attentively to his every lessons. Yamamoto, Ryohei and Chrome were also being taught by their Ninth generation counterparts on their tasks in the family after Tsuna's real Inheritance Ceremony, even with Tsuna's protest that there wouldn't be one, ever. Hibari-san, probably while looking for someone to fight, became involved in the training of the new recruits for the family. If that wasn't chaos enough, Muruko and the Kokuyo Gang also appeared, together with the Varia.

For weeks after that incident, the Vongola Infirmary, which was famous for being able to handle thousands of injured people, became very busy. (Tsuna even proposed to allot more money on the budget for medical research. He didn't need hyper intuition to know that the Vongola would need it in the future.)

And with all these happenings in his vicinity, the next-in-line boss of the Vongola Family was locked in his newly furnished office with a high pile of paperwork and a green gun pointed at his head as he signed those documents as: _Tsunayoshi Sawada, Vongola Decimo_. (He rejected the title Neo Vongola Primo because it sounded flashier than Vongola Decimo.)

After Nono recovered, he asked Tsuna if he was ready to inherit the family, in which Tsuna declined with a violent shake of his head. The Ninth Boss just gave him a fond smile, as if to say, ' _You really do not know when to give up'_.

Tsuna thought that his life would be easier when they returned to Japan after being in Italy for two months. But the curse of the paperwork followed him as Nono still sent him some documents to be analyzed and signed weekly, which seemed to increase as time passes, much to his annoyance and his sadistic tutor's glee.

One year had passed since his time in Italy and the paperwork that usually came in just a thin envelope now needs a box. There were times when certain decisions about the Family were forced on him. Matters concerning the Vongola Corporation, as the family's cover in the outside world, also became Tsuna's responsibility. The Vongola Alliance Meetings and Vongola Corp. Board of Director Meetings in which Tsuna needed to make an appearance (because Nono feels faint-hearted and couldn't come, Reborn had said, but Tsuna never believed the hitman's excuse) also increased gradually.

Right now, he moved through the motion of doing his homework and paperwork in the evening even without Reborn's supervision (which means that there were no gun pointed at his head) most of the time but he couldn't get the nagging feeling that the Ninth and Reborn planned the fainting episode last year to somehow pass a little bit of the Ninth's responsibilities to him (which explains why even though their boss claimed to have fainted, none of the guardians were worrying about his health), and gradually increases them until Tsuna's already managing the whole Family without him realizing it. Of course he still says his favorite line of _'I'm not going to become a mafia boss.'_ from time to time, but the conviction behind the words almost disappeared completely and became a way of clinging to his sanity.

Gokudera also seemed at-home with his self-declaration as Tsuna's right-hand man, helping Tsuna with some paperwork, bringing coffee when Tsuna was sleepy, sending the documents back to Italy in Tsuna's stead, serving as Tsuna's bodyguard on meetings (though he was adamant on not needing one), and establishing communications with the other guardians, who were always travelling. Especially Hibari-san, who had formed the Foundation with the members of the Disciplinary Committee when he graduated from high school and true to his nature as the cloud guardian, was always away in some place or another doing whatever he wanted to do. Tsuna only learned of Hibari-san's location when he received paperwork from Kusakabe-senpai containing information about illegal dealings, new weapon inventions and technology breakthroughs.

Yamamoto was recruited on the national junior baseball team and was always on training camp, but the natural-born hitman still met with them despite his busy schedule. Ryohei had discovered a new fascination with travelling since graduation, and was always training somewhere far. The only guardians near them was Lambo, who was living in his house and Chrome who somehow found herself always included in Kyoko, Hana and Haru's somewhat odd group.

Tsuna sighed again and looked at his table, where another pile of paperwork appeared. "Another pile?"

"The Varia went on a mission to subdue an escaped informant with sensitive information regarding the Vongola. They destroyed two buildings." Reborn shrugged, as if the matter was an everyday occurrence.

 _It probably is_ , he thought.

"Fine, but Reborn…"

"What?" The hitman turned his eyes on him and adopted a look of innocence. As if Tsuna could believe that with his situation right now.

"Can you release these chains?" Tsuna glared at the chains tying him to his chair. They were reinforced steel, and was created by the combined genius of both Shoichi and Spanner, which could only be unlocked by a specific signature flame, and in these chains' case, Reborn's. It had already been two weeks since he had successfully escaped Reborn and his paperwork and had managed to hide for more than three days. It seemed like the hitman still bear a grudge that Tsuna was able to one-up him. "I promise not to run away this time."

Reborn looked to be pondering his request. Tsuna hoped that a miracle would occur and his tutor would let him go this time. "How about… No?"

And accompanied by a gust of wind, his tutor jumped down the window and out of his field of vision to do whatever it was that evil-hitman-teenage tutors do when they're not tormenting kind and innocent students.

"Reborn!" he whined (even he thought the hitman couldn't hear him, but it was Reborn, and nothing is impossible to him) trying to escape his chains but failing miserably. "I just wish for a brief vacation from paperwork."

He tried on focusing on signing those blasted paperwork. Maybe if he finished them early, Reborn would pity him and let him out for once.

And then, out of nowhere, his intuition flashed ' _DANGER_ ', as he heard Fuuta's warning of "Tsuna-nii, dodge!"

There were a lot of things going through Tsuna's mind as he watched that Purple Bazooka made its way to where he was sitting. One was that he had forgotten that his very dangerous and disaster-prone siblings were in the same room as him, which always resulted in catastrophe in one way or another. Two was his previous trip to the future where he woke up on a coffin, and he shuddered at the thought of finding himself inside that place again. Three was that he could probably take the chair he was tied to and try to dodge, as Fuuta had suggested, but the thought of even five minutes away from the paperwork seemed like heaven that was tempting Tsuna not to move. The last was a memory from the edge of his mind, when Giannini visited them three days ago. He vaguely recalled the inventor holding Lambo's bazooka saying something about an inspection…

His eyes widened to an impossible size at the implication of those words, Gianini Bazooka Possible malfunction. But by then, it was already impossible to escape, so the to-be tenth boss of the most powerful famiglia in the world was enveloped in a pink smoke, and the three kids watched as the said smoke cleared and no Ten-year older Tsuna-nii was standing there.

Really, the gods might love messing with Tsuna too much. His wish for vacation was granted, but not in the way he was expecting it.

* * *

 **Approximately, 150 years ago. Italy.**

Giotto, the founder of a vigilante-group-turned-mafia-organization, looked outside the window of the second floor parlour of the Vongola Mansion. For some reason, an uneasy feeling was growing in his chest. It didn't bode well, since the last time this happened, the town was attacked by a rival family, and if it weren't for Alaude's information network and immediate response, the damage would have been severe.

There were times when his abnormal intuition seemed to really help them, but during times like this when he was forced to wait and do nothing while knowing something was happening nearby was the worst.

"Giotto, is there something wrong?"

Giotto looked away from the window to see Asari's concerned face. It seemed that he was worried about Giotto's apparent unrest. Everyone in the room stopped what they were doing to stare at the both of them.

"Nothing." He smiled to reassure them. "Nothing's wrong." _I hope._

* * *

*Gelaro of the Bertesca Famiglia, This is a game-only character.

 **Additional A/N:** The next two or three chapters would be uploaded sometime this fortnight, since I just need to proof-read those, but the following chapters will probably be released only if I have found the time to write them.


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